1. Field of the Invention
One aspect of the present invention generally relates to a method and system for estimating spare parts costs, and in certain aspects, a method and system for estimating spare parts costs of a machine.
2. Background Art
The process of manufacturing products typically involves the use of machines, which usually include a multitude of components, otherwise referred to as parts. Many of these parts can be repaired and/or replaced several times during the life cycle of the machine. For instance, many mechanical and chemical parts need to be repaired and/or replaced as they are susceptible to wear out, failure and/or aging. Manufacturers and/or suppliers often procure and inventory spare parts so that the failed or aged part can be replaced in a timely and efficient manner.
Estimating the number of replacement parts that are needed during the life cycle of a machine is critical to the cost-efficient procurement and inventory of spare parts, as well as other business objectives. Manufacturers and suppliers typically perform estimates on costs associated with the life cycle of machines, which are otherwise referred to as reliability and maintainability life cycle costs (LCC). However, these cost estimates often do not include a calculation of estimated spare parts needed. When the estimated LCC includes a spare parts estimate, the spare parts estimate may be incomplete and/or inaccurate, especially if the machine is based on relatively new technology in which reliability data on some of the replacement parts is scarce or unknown.
Without accurate and complete spare part usage estimates, a significant difference in actual and expected life cycle costs may arise. This discrepancy may cause a number of business problems, including, but not limited to, inefficient use of resources, lack of funds for necessary spares and maintenance, and negative effects on profitability of the manufacturing process.
Moreover, inaccurate estimates of life cycle costs can impair business decisions regarding the acquisition of machines. Acquisition decisions are typically made by taking into account the life cycle costs in addition to the acquisition price. Often, tradeoffs are made between the acquisition costs and the long term operating costs. In order to effectively make these tradeoffs to arrive at a sound business decision, the life cycle costs, which include the long term operating costs, must have a relatively high level of accuracy.
While life cycle cost models have been proposed and implemented on computer systems, these systems do not adequately address the spare parts estimation issue. Many of the systems do not address spare parts cost estimation at all. Moreover, these models are very complicated, requiring a sizable amount of input and computing power. For instance, many life cycle models have been implemented on mainframe computers.
To the extent that some of these systems do address spare part usage estimates, the estimates are based on faulty assumptions. For instance, at least one system assumes that failure rates remain constant over time, which is typically not the case.
Instead, what is needed is the use of a failure distribution which produces more accurate spare part usage estimations. While failure distributions have been used to model the failure of single components, they have not been utilized in the calculation of machine life cycle costs.
In light of the foregoing, a method and system for estimating spare parts costs with failure distributions is needed. A method and system is also needed to estimate the life cycle costs of a machine having a number of parts replaceable by spare parts.